/*
 * Copyright 2020 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.optaplanner.core.impl.score.stream.drools.common.rules;

import java.util.Objects;

import org.drools.model.Rule;
import org.optaplanner.core.api.score.stream.bi.BiConstraintStream;
import org.optaplanner.core.impl.score.stream.drools.common.BiTuple;

public final class RuleAssembly {

    private final Rule rule;
    private final Class[] expectedJustificationTypes;

    RuleAssembly(Rule rule, Class... expectedJustificationTypes) {
        this.rule = Objects.requireNonNull(rule);
        this.expectedJustificationTypes = Objects.requireNonNull(expectedJustificationTypes);
        if (expectedJustificationTypes.length == 0) {
            throw new IllegalStateException("Impossible state: Rule (" + rule + ") expects no justification types.");
        }
    }

    public Rule getRule() {
        return rule;
    }

    /**
     * Determines the types we expect to see as the result of {@link #getRule()}.
     *
     * <p>
     * Example 1:
     * For a {@link BiConstraintStream} before regrouping, we expect this to return an array of A and B's fact type.
     *
     * <p>
     * Example 2:
     * For {@link BiConstraintStream} after regrouping, we expect this to return an array consisting of only
     * {@link BiTuple} class.
     *
     * @return never null
     */
    public Class[] getExpectedJustificationTypes() {
        return expectedJustificationTypes;
    }
}
